The spinal column is a highly complex system of bones and connective tissues that provide support for the body and protect the delicate spinal cord and nerves. The spinal column includes a series of vertebral bodies stacked one atop the other, each vertebral body including an inner or central portion of relatively weak cancellous bone and an outer portion of relatively strong cortical bone. Situated between each vertebral body is an intervertebral disc that cushions and dampens compressive forces exerted upon the spinal column. A vertebral canal containing the spinal cord is located behind the vertebral bodies.
There are many types of spinal column disorders including scoliosis (abnormal lateral curvature of the spine), excess kyphosis (abnormal forward curvature of the spine), excess lordosis (abnormal backward curvature of the spine), spondylolisthesis (forward displacement of one vertebra over another), and other disorders caused by abnormalities, disease or trauma, such as ruptured or slipped discs, degenerative disc disease, fractured vertebrae, and the like. Patients that suffer from such conditions usually experience extreme and debilitating pain, as well as diminished nerve function.
A noteworthy trend in the medical community is the move away from performing surgery via traditional, “open” techniques in favor of “minimally invasive” or “minimal access” techniques. Open surgical techniques are generally undesirable in that they typically require large incisions and high amounts of tissue displacement to gain access to the surgical target site, which produces concomitantly high amounts of pain, lengthened hospitalization (increasing health care costs), and high morbidity in the patient population. Less-invasive surgical techniques (including so-called minimal access and minimally invasive techniques) are gaining favor due to the fact that they involve accessing surgical target sites via incisions of substantially smaller size with greatly reduced tissue displacement requirements. This, in turn, reduces the pain, morbidity, and cost associated with such procedures. One such minimally invasive approach, a lateral trans-psoas approach to the spine, developed by NuVasive®, Inc., San Diego, Calif. (XLIF®) has demonstrated great success in reducing patient morbidity, shortening the duration of hospitalization, and speeding recovery time if it is employed.
In some instances, it is desirable to perform a lateral lumbar interbody fusion procedure with supplemental posterior fixation. This may require re-positioning the patient from the lateral decubitus position to the prone position which can significantly increase operative time among other things. It is therefore advantageous to perform so-called “single position spine surgery” in which the lateral lumbar interbody fusion procedure and the posterior fixation procedure are performed while maintaining the patient in the lateral decubitus position. In some instances, patient pathology (for example, spondylolisthesis) presents significant challenges to single position spine surgery. What is needed are methods and instruments that facilitate single position surgery in a wide variety of pathologies. The present invention addresses the aforementioned needs.